The town I grew up in is very old. There are a few buildings still standing that date back to the 11th century, some perhaps even older than that. There’s also a well preserved part of the medieval town wall, and below that are known to be Roman ruins. And it was in a rarely frequented part of that wall, in the shadow of an equally ancient bridge, where the door was located.

I’ve known the door since I was a kid. It was a weird door, old and moldy and made of massive oak planks and for some reason there was a deer skull nailed to it. The really weird part however, was that it didn’t seem to go anywhere. There were no windows or any other signs that there was anything at all in the wall behind the door. It didn’t even have a proper frame; it just stood there, let a few centimeters deep into the wall, looking oddly out of place.

The door both frightened and fascinated me. I often took detours on my way home from school to go past it and look at it, but I never dared to open it or even get too close. And there was that one thing about it that ticked me off throughout my entire life: nobody else cared about the door. Nobody else even seemed to notice it was there. I was always alone when I went to visit the door, and when I asked people about it they never seemed to know what I was talking about.

Years went by until one day – I was well in my teens by then – I finally mustered the courage to try and open the door. It was a warm summer afternoon and as usual I was alone under the bridge where the door waited. I had stood there for the better part of an hour, just staring at it, until at long last my curiosity exceeded my fear and I went right up to the door and pulled on the handle.

After a short initial resistance something seemed to go ‘crack’ and the door opened very smoothly. A gust of cold, stale air went past me from the inside, and for a moment I thought I heard a voice muttering something incomprehensible, but when I looked around, I was still alone. Behind the door was a narrow stone staircase leading down beneath the wall, dimly lit by the little daylight that passed through the door. I took a deep breath and just started down before I could get a chance to change my mind

At the bottom of the stairs was a single room, cold and dark and almost empty except for a table, two chairs and a sort of shelf, all made of wood and all of them empty. There was also a lot of dust, but still something about the room felt as if someone had been in here not too long ago. Maybe it was that there weren’t any cobwebs, although I only realized that much later.

Needless to say I was quite disappointed. The great mystery of my childhood had been revealed as something completely mundane, all the magic taken away. On the way home I told myself that I would never waste a thought on that stupid door again, but on the next day the killings started.

In the following weeks a strange series of deaths occurred in the town. The police started an investigation, but they weren’t even sure if it was actually murder. The victims were all found fully clothed, but their bodies covered with perfectly spherical, tennis-ball-sized burn marks.

A few witnesses reported seeing a strange man in a faded blue suit and matching top hat near the sites of death and the police soon wanted him for questioning, but he was never properly found. Nobody seemed to know him, nobody had ever talked to him and those who had seen him had only glimpsed him for a few seconds without a chance to approach him.

Of course I didn’t have any reason to suspect a connection between those deaths and my door. Not until I ran into the stranger myself.

One evening when I was coming home I had to stop on the stairs to my flat because I was gripped by a sudden nausea. For a few seconds my stomach cramped, I saw bright points of light flickering before my eyes and I thought I was going to throw up right there. But then the feeling subsided and instead I smelled something burnt. As I continued up the stairs the smell intensified to a noxious stench. When I reached the top I saw that the door to my neighbour’s flat was ajar and the stench appeared to seep right through the crack. By now it was so heavy I imagined I could almost see it.

When I stepped towards the door to have a look I noticed there was someone moving inside. Someone who wasn’t my neighbour.

Ever so carefully I snuck up to the door and peeked through the crack. And there he was alright, just like the newspapers had described him, the strange man – if it was indeed a man – in the blue suit.

What I could see of his skin was waxy pale, but most of his face was covered by a bushy black beard, so dense that you couldn’t even see his mouth unless he opened it. Somehow he must have noticed me, because just then he turned towards the door, flashed a smile full of surprisingly clean white teeth in my direction and said something in a language I didn’t understand.

That was when it struck me. That voice. It was the exact same voice I had heard when I opened that door under the bridge! I know it sounds crazy, but in that moment I knew that he, or it, had been in that room under the wall, imprisoned for god knows how long and I had released it.

After a while the killings in the town ceased. The case was never solved and eventually filed away and forgotten, but not by me. I’ve been reading the news and I’ve seen the occasional reports of killings done in exactly the same fashion in cities all over Europe. Apparently he eventually got bored of our little town and moved out into the world.

I still don’t know what the hell he is, why he does what he does, or why he spared me, but I know this: He’s still out there and that’s my fault.